Orthodontic treatment for patients with uni- or bilateral congenitally missing lateral incisors is a challenge to effective treatment planning. The two major alternatives, orthodontic space closure or space opening for prosthetic replacements, can both compromise aesthetics, periodontal health, and function. The aim of this retrospective study was to examine treated patients who had congenitally missing lateral incisors and to compare their opinion of the aesthetic result with the dentists' opinions of occlusal function and periodontal health. In this sample, 50 patients were identified. Thirty had been treated with orthodontic space closure, and 20 by space opening and a prosthesis (porcelain bonded to gold and resin bonded bridges). The patient's opinion of the aesthetic result was evaluated using the Eastman Esthetic Index questionnaire and during a structured interview. The functional status, dental contact patterns, periodontal condition, and quality of the prosthetic replacement was evaluated. In general, subjects treated with orthodontic space closure were more satisfied with the appearance of their teeth than those who had a prosthesis. No significant differences in the prevalence of signs and symptoms of temporomandibular dysfunction (TMD) were found. However, patients with prosthetic replacements had impaired periodontal health with accumulation of plaque and gingivitis. The conclusion of this study is that orthodontic space closure produces results that are well accepted by patients, does not impair temporomandibular joint (TMJ) function, and encourages periodontal health in comparison with prosthetic replacements.